Re: [PATCH v2] drm/i915: Optimistically spin for the request completion

Chris Wilson
2015-03-12T09:07:49Z

On Wed, Mar 11, 2015 at 09:18:19PM +0000, Chris Wilson wrote:
> Arguably busy-spinning on an idle system isn't totally evil, but it
> certainly is likely to come at a power cost. On the other hand, spinning
> is relatively rare outside of benchmarks. Rare enough to be useful?

As a counterpoint, I plugged in the qm_pos trick we use for lowlatency
dma interrupts (gmbus, dp-aux) and found no improvement at all over a
plain interrupt driven __i915_wait_request.
-Chris

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Chris Wilson, Intel Open Source Technology Centre